The present invention relates a sheathed synthetic fiber rope, preferably of aromatic polyamide, and a process for manufacturing it.
In materials handling technology, especially on elevators, in crane construction, and in open-pit mining, moving ropes are an important element of machinery and subject to heavy use. An especially complex aspect is the loading of driven ropes, for example as they are used in elevator construction and for suspended cable cars. In these instances the lengths of rope needed are large, and considerations of energy lead to the demand for smallest possible masses. High-tensile synthetic fiber ropes, for example of aromatic polyamides or aramides with highly oriented molecule chains, fulfil these requirements better than steel ropes.
Such a sheathed synthetic fiber rope has become known from the European Patent document 0 672 781 A1. There, the synthetic sheath is applied by extrusion in such a manner that a large surface of adhesion to the strands is formed. However, when the rope bends on the rope sheave or pulley the strands perform compensatory movements which, under certain circumstances, can cause relative movement of the strands of different layers of strands. These movements are greatest in the outermost layer of strands and particularly when the drive torque is transferred by friction to the section of rope lying in the angle of wrap of the rope sheave, can cause the sheath to lift off and form pile-ups. Such a change in the structure of the rope is undesirable because it can cause the rope to have a short service life. The same applies to ropes wound on drums as they are used in mining.
The problem underlying the invention is that of proposing a sheathed synthetic fiber rope with a long service life, as well as a method for producing such a rope.